1. Field of the Invention
This invention relates to a device for stabilized opening and closing of a sliding panel that can be used for a fully openable and collapsible door for partitioning a building, a rain shutter or a gate door exposed to rain water.
2. Prior Art
A device for automatically opening and closing a sliding panel of the above mentioned category has been proposed in Japanese Patent Application No. 62-272542.
Such device includes a rubber cylindrical driving roller rotatable both clockwise and counterclockwise and driven by a motor and a cooperating rubber cylindrical pinch roller arranged in contact with the driving motor. For example, a horizontal reinforcing member of a sliding panel made of aluminum alloy is pinched between the two rollers and forcedly moved away or back to open or close the sliding panel as the driving roller is rotated in opposite directions.
However, such device is accompanied by a drawback that it cannot smoothly open or close a sliding door, since the driving roller idly rotates without effectively moving the sliding door, even through the rubber of the rollers provides sufficient friction against the sliding panel pinched therebetween. Attempts for improving the performance of such a device by changing the distance between the two rollers that press and hold a sliding panel have proved to be unsuccessful.
Such a device provides a poor performance particularly when it is applied to a large sliding door, a heavy gate door, a collapsible sliding door constituted by a large number of panels or a slide panel with a heavy load, indicating that this particular drawback has to be eliminated if such a device is made feasible for practical applications.
It is therefore an object of the present invention to provide a device for enabling stabilized opening and closing of a sliding panel that ensures smooth opening and closing operation regardless of the type of the door to which it is applied.
The present inventors, as a result of intensive research efforts, came to find that the driving roller of such a device becomes idle when the area of the sliding panel pressed and held by the driving and pinch rollers is wet due to dew drops, rain water or moisture in the atmosphere, which conditions nullify the effect of frictional resistance of the rubber driving roller against a sliding panel made of aluminum alloy, steel or synthetic resin, even though the frictional resistance is of a sufficient magnitude for opening and closing such a sliding panel.